Fractional crystallizer



Oct. 7, 1952 D. MGKAY FRACTIONAL CRYSTALLIZER Filed Deo. 21, 1949 AIM IN VEN TOR.

D.L. MEKAY A TZQRNE YS Patented Oct. 7, 1952 FRACTIONAL CRYSTALLIZER.

Dwight L. McKay, Bartlesville, Okla., assignor to l,

Phillips Petroleum Company, a corporation of l Delaware .Application December 21, 1949, serial Nc. 134,225 'if lThis invention relates to crystallization apparatus. Inone specic aspect it relates to 4an apparatus ijorjthe separation of mixtures by multistage crystallization. .In a speciiio embodiment. it relates to an apparatusfor eliiciently moving a granular mass of crystallized materialthrough a fractional crystallizer. I v

, In the separation of mixtures of compoundsby fractional crystallization, various types of apparatus have been constructed for establishing contact between a massof the crystallized material moving in one direction and a mother liquor mov,- ing in the opposite direction. Usually these devices `employ a flight conveyor or auger for moving the crystals. In most, horizontal type crystallizers, a higher-melting fraction is removed from one end, a lower-melting fraction is removed from the opposite end and the feed is introduced at an intermediate point. The apparatus may be jaclsveted` *to` abstract heat through the walls'and form crystals in the liquid body, which usually fllls -the apparatus. The crystals that form `in contact with a motherliquor are, ordinarilyfthe higher-melting fraction. In the case of eutectic mixtures. the crystals may or may not bey the higher-incitingV component but will be `that component presentin excess of the eutectic ratio. i

-, One of the principal difficulties with the devices or the prior artis that the crystal movers are not eililcient if the ratio of solid to liquid becomes too high. liliihen the amount ofsolid material is too high, the nights. of the conveyors bridge over with' crystals and no crystal movement occurs. It

is fnecessary, ifrseparation is to occur, that the crystals or solid granular material be continuously moved toward the outlet for the higher-melting fraction and that the remaining liquorv be displaced'toward the opposite end, where the lowermelting fraction is withdrawn.

` I hav'erund thattne flights of conveyors used inthe fractional;crystallization 0I materials often stick in the open or closed position due to agglomeration and'packlng of crystals. I have discovered 'that the movement.y of ilights restricted in this manner may be restored by a slight impetus appliedthereto to break loose the flights allowing themtto complete their opening or closing by the force `of thesolution and crystals thereon. I have iurtherdiscovered an apparatus and method for operating same for applying the needed additional force for causing initiation' of movement of the vanes of a conveyor flight. My inventionfis particularly adapted to use in a crystallizer that is totally fenclosedand hasa freezing section near one ,end and anzadlbatic sectionthrough which s claims. (c1. 2?.;2735

thecrystals must be moved before reaching the product outlet. i f

, The principalI object 0I my invention is to provide a simple and efclent apparatus for moving crystals through a liquid-full container and displacing liquid` in the oppositedirection.

Another objectis to provide a conveyor for use in multi-stage crystallization` apparatus.

Another object'isitopmvide a crystal conveyor for moving the solids oa-slurry to one end of the apparatus countercurrent tothe liquid.

Another. object is to provide an improvement iniractional crystallization apparatus whereby movement of the varies of the conveyor flights may be assured at all times. y

Still another object is to'provide an apparatus for providing a force for causing initiationoi movement of the vanes of conveyor flights.

, Other objectsand advantages of my'invention will be apparent from the accompanying disclosure anddiscussion.

vFigure l is alongitudinal sectional view of a horizontal type crystallizer showing the crystal conveyor in elevation.

.Figure 2 `is a detailed cross sectional view of a portion of the crystallizer shown in Figure l showing the construction Iand means of operating one flight of the conveyor of my invention.

Figure l3 isa detailed view partly in section and partly in elevation taken along line 3-3 of Figure 2.

Refer now to Figure 1. Reciprocating hollow support or conduit II) extends through end wall I I through the length of the crystallizer and out end wall I2. Conveyor flights I3 are spaced along the lengthV of support I0 within the crystallizer and are-secured thereto. Stufling boxes Ill and I6 seal the spaces around support I0, 4which is caused to reciprocate by the movement oipitman I1 and connecting rod I8, actuated by drive means not shown. The reciprocating support I0 may be made up as aunit or it may be made up in sections of the"y same or pyramiding ,size joined tosuch as refrigerating g coils Aor electrical Aheating elements as are wellfknown-to `those slilledin `the art.` Number .30. indicatesmeans ior applyin CoolingI initial impetus to the movement of vanes of flights I3. These means may be hydraulic cylinders with pistons actuated with a liquid or a gas, or they may be solenoids such as with double windings for actuating the piston back and forth or other types of motors. As indicated in this drawing, couplings I 9 may be so constructed that outlets for4 thehydraulic material are placed therein for ease of assembly. In this manner only two pipes are needed for carrying the hydraulic fluid to cylinders 30 and for transmitting the pressure applied thereto. which is fed hydraulic fluid (liquid or gras) through line 32 is actuated by thelug's-SS vand 34 on support I contacting diverter "I 5.j These lugs l are so positioned that at the start yof each intake and pump stroke the diverter which controls the direction of flow of fluid is reversed. In this manner the vanes of flights I3 are aided in assuming" a retracted position when moving in one direction and an extended position when moving inthe 'opposite direction. Line leading -fromffv'alvel isprov-ided to relieve pressure onthe line opposite that upon which pressurefisr--being instantly appliedi" It is'within-thel-'scope of' my! invention, when utilizing` 'a-hydraulic fluid vto actuate' the pistons in cylinders 381 touse only.' one-inlet to the cylinders; using: positive `pressure to move the piston in' one directionand a'negative'pressure to movefitv in the other direction;

The terrn'lconveyorfightv as' u s`ed` herein refers to'the vanes, -ther mans by which the -vanes are' attachedf't'o"hollowsupport" Il); and the parts of" the vanes including@ the perforate areasl and the outer edges which whenthefva'nesare e'X- tndediscrape crystalline-'material fromfthe walls of tne-rysta11izerz- Theconveyor1f1ightfof the instantapplioatiorr-i'ssimilar-to that disclosed inf-Copending ooassi'gned--application Serial No. 111,618; byu; A. Weedmait Howeverfin the instant application, the openingandclosingloffthe vanes isnot* solely dependent uponl the reciproeatingv motion of the vanes; but is-positively 'controlled by motor means. Y v Refer now to -Flg-ur-2a`- Inlfthis vdraWin'gthe sameJ -piecesof 1 apparatiis as'disclosedinflji'gurex l.I willJv beJsimll'arly huinbefed. Act'uatinggfluid is passed through support Y I Uflby means-lof 'pipes' 36 and 37'- up" to the outlets located 1in'A couplings -I 9. From -t-hese outlets 'thef 'u'id i's Y passed' through tubes 38 and 38 alternately. These tubes connectf`withcylinders, thrughthe` inlets; there- `for,` which are pivotallyattachdltol r'o`d Illby hingesssfandfwhieH-eontain-.pistons 41o-.attached to connecting rodi 41 when in 'turnfarefpivotally attachedlto vanes42 -byjhinges 45'.'- In'l operationr when -pr'es'sureis`v aiop'lied4 through pip'ef 37.3 and. tube-Sthepistonfd iscused tom'ovei'nthe direction ofTtheY-'end otf cylinder 30 andf'van'el 42fis1 extendedagainst or veryv near to the 'Wa11l43of' the crystallize'r- To retract? thevane movement is initiated byl applying pressure `through pipe 361 and tubeY 38 thus ffcausingthe piston? tobe: movedA to'theotlier-er'id'offcylinderff j v Refer now'. to lFigivxre-B:` l In' this draw'i'rg,Y the. samepiecesofafpparatus las :are disclosed` in Fig.- ures 1 and I2 will-b similarly f'number'ed'. Y Vertically extendirigispokes 44 rigidlyattached 'to sup'- por't `I 0 are positioned f such 'that iloop'sfd Sfrigidly; attached to vanes 112i` may f be` loosely?- securedv thereab'out- Vah`s`q2consist"offporous'screen 47 whichf is attached' to Ari'ng 48l'an`dbari 49': Ring 48 Fis so constructed-thatwhen the' vanes are' ex`-` tended 'one-edg'efther'eof lies inafpositionsubstantiallyparal'lel totl-'w'alls'- 43 fof th cly'stall'zers.

Diverter] valve 3|v to` c aciia This device is designed for the purpose of moving a mass of granular solid through a confined body of the mother liquor, which is thereby displaced in the direction countercurrent to the movement of the crystals. By use of my apparatus sticking of the vanes of the conveyor ights is overcome even when the crystal solids content of the mother liquor is relativelyhighf. Y

In carrying out fractional crystallization utilizing the apparatus of my invention, feed is introduced to a crystallizer of the type shown in Figure' 1 .intermediate the freezing zone 23 and the melting zone 27 of the crystallizer. On the pump *stroker the crystals formed in the freezing zone are scraped from the Walls by the rigid outer rings 48 and are pushed forward through the crystallizer toward'lmelting zone 27 by the perv forate vanes of the conveyor flights in an extended position. At the same time liquid is displaced in the opposite direction and iiows through the perforations in the vanes'. The'crystals are melted in xriel-tin'gzonev 27 and a' portion -of the li'qi'licl, richer than the feed in the crystallized com-ponent, is withdrawn through conduit 2I from the end` of Vthecrystallizer adjacent melting zone 27,` Liquid poorer-than the feed in the crystallized component is withdrawn through conduit 20 from the end ofthe crystallizer'adjacent freezing zone 23.. On-the reverse or intake' stroke; thevan'es are lretracted forming. an' opening around'the sides ofthe vanes to allow both crystals and liquor to pass.

My deviceis operable as'long as the'lmixtu'e in -thecrystallizer isy maintained in a slurry AIf formed crystals are melted '-in the-outlet end of my apparatus and the inlets and-'outlets closed, itmay'be operated-at total reflux." If the lcrystals'are-not melted in the apparatus but are 1removedasl solid-material, t'is obvious that their removal must occur-'at-the same rate-that they are'd'elivered' tothe end of thev apparatus.- 'Otherwise,A there would be a building `'up-ofI solid material inthe end -of the apparatus'which couldresult lin damage to the conveyor flights.v

The perfoi'ate piston may be mad'efof forazninousrriaterialwhich Y willpermit thevflowv o'f liquid' therethrough' without-substantial. resistancefan'd at the same time will-retain granular material-. It doesnot'effect the operation'itsomev small crystals do Ipass through v the piston "along with -th'e liquid. These crystals are probably-"1m"- pure and more closely`-` approximate theicomp'o's'i'- tionA ofl the liquid thanj do lthe largerv crystals whichaije retained von the* piston. I'have found that a 20"'or 30 mesh4 screen isfexcellent forK this purpo'seji" t In Figure 1 my apparatus isshown'in a -liorieA zontal position. However, it may bel operated "in a vertical or inclined position and in someiinstances.. such position'sare 'preferable'. My apparatiisjisfnot'lirriit'edjto' operating at a'nylcfe'r-y tain "pressure but isoperable at' constant orpul satin'gy, pressures ranging frothy atmosph'eric`A to superatmospheric pressures. Itiis possible to use al.fee'ol:containingcrystalline -rriateri'al in! which event ythe operation of my .device Ais still the. same. It is also possible totoperatel the apparatus. in

non-horizontal` positions,Y as described above.. with the .meltingsection at the elevatedend. y

Additional means for applying-impetus to'fthe movement-"of the' vanes of the` conveyor flights may: beused. For example;- one hydraulic-cylinder' or, solenoid: positionedparallelgwithfthe condui-t towhich the conveyor flights are:i attached veyor-nights. This rod vinaybe axiallypositioned within the'hollow! conduit'to which the nights lare attached.@Connecting rods are hinged; thereto for transmitting movement of the 'rods -to .the vaines.l l'The'se `connecting -`rods .extend -throug-h slotsin the hollow conduit and are attached to the vanes of the conveyor nights.' `Suitable means snchsas"conventional` bellows are placed around each-connecting rod where' it passesthroughfthe hollow `conduit to prevent-the passage of material ntovtlfieA conduit. "Thelother similar'apparatus hasl the rod outside the hollow conduitandsimilarly-'attached to each ofthe vanes of the' conveyor night Such antarrangement of-.apparatus mayhave 'the rod actuatedvas by a cam or'byrthe hydraulic "or electrical means previously described for use with each vane, but of a size sunicient to supply-the necessaryforce to move all the vanes.

Although the apparatus lhas vbeen described and exemplined in'fternisof its'preferred modincations, it is understood that various changes may be made without departing from the spirit and scope of the disclosure and of the claims.

I claim:

1. A fractional crystallization apparatus which comprises, in combination, an elongated enclosed container, a product outlet `adjacent each end of said container and a feed inlet intermediate said ends, means for addingheat to said container adjacent one end thereof, means for abstracting heat from said container along a portion thereof between said feed-inlet and the unheated end, and means for movingsolid granular material through said container from the cooled to the heated end which comprises a reciprocating support extending axially through said container, a plurality of foldable perforate conveyor nights hinged at spaced intervals to said support, said foldable conveyor nights beingl adapted to close on the intake stroke and open on the pump stroke of said nights, and a motor pivotally attached to said support and said conveyor flights for applying impetus to the closing and opening of said conveyor nights.

2. A crystallizer according to claim 1 wherein said means for moving solid granular material through said container comprises, in combination, a reciprocatingsupport extending axially into said crystallizer, a plurality of foldable perforate conveyor flights disposed at spaced intervals along said support and secured thereto, each said flight comprising a pair of vanes, and a hydraulic operated reciprocating piston pivotally attached to each of said vanes, each of said pistons operating inside a cylinder which is pivotally attached to said support for applying impetus to the closing and opening of said varies.

3. A crystallizer according to claim 1 wherein said means for moving solid granular material .through said container comprises in combinatienda reciprocating support `extending axially through isaidcrystallizer, a plurality; .of foldable perforatel conveyor .nights horizontally disposed. at spacedfintervals along said support and secured'theretojeach of saidfnights comprising a pair-of 1 movable vanes which whenlaid nat take an "ellipse-liketsshape;,the longest' -diameter of which is greater than the diameter of,.said crystallizer, 'a solenoid pivotally attached throughfa linkage -lto said .vanes and said support for applying?` impetus :to the opening and closing of said vaines-'and means for actuating" aid solenoid for; applying impetus. l Y i '4.- A crystallizer according toclaim` 1 wherein saidmeans for moving solid-,granular material through :said container comprises, in combination, a; reciprocating rig-id support extending from 'one `en'd longitudinallyv into said crystallizer-,a pluralityl of foldable perforate conveyor nights disposed atfspaced intervals alongl said'supp'ort andfsecured ithereto,.` each said'A conveyor night comprising a pair ofvanesuwhich when laid' nat take `an ellipse-like shapet-he longest diameter ofi-which is greaterthan ,the diameter of.:said crystallizer,Y and a `hydraulically'operatedjreciproeating piston: attached through a linkage: to said vanes' i said conveyor nights and t'o said reciprocatingfsupport for applying impetus to. the .closing and opening of said conveyor'nights.

`il. A crystallizer according to claimA 1 wherein saidsmeans 4for moving'solid granular material through said v.container comprises in combinatienta reciprocating `hollow lsupport extending through thenends of said .crystallizer and/being axially positioned therein, afplurality of.` foldable perforate conveyor nights each comprising a pair of vanes which when laid nat take an ellipselike shape the longest diameter of which is greater than the diameter of said crystallizer, a hydraulically operated reciprocating piston attached through a linkage to the vanes of said conveyor nights and to said hollow support for applying impetus to the closing and opening of said conveyor nights, means for actuating said piston at the beginning and end of each pump stroke, and means for actuating said reciprocating hollow support.

6. A fractional crystallizer according to claim 1 wherein said means for moving solid granular material through said crystallizer comprises a reciprocating hollow support extending axially through said crystallizer, a plurality of foldable perforate conveyor nights disposed at spaced intervals along said support and secured thereto, said foldable conveyor nights being adapted to close on the intake stroke and open on the pump stroke of said hollow support, said nights comprising a pair of vanes which when laid nat take an ellipse-like shape the longest diameter of which is greater than the diameter of said crystallizer, hydraulically operated reciprocating pistons pivotally attached to each of said vanes and to said support for supplying impetus to the opening and closing of said vanes, and means for actuating said pistons at the start of said intake and pump strokes and thereby applying impetus to the movement of said vanes.

'1. A fractional crystallizer according to claim 1 wherein said means for moving solid granular material through said crystallizer comprises a reciprocating hollow support extending axially through said crystallizer, a plurality of foldable perforate conveyor nights disposed at spaced intervals along said support and secured thereto, said foldable conveyor nights being adapted to close on: the intake. strokey and open 'on the pump stroke-i'A of saidA "hollow support;y said nights comprising a pairzof'vaneswhich when. laid attake an. ell'ipselike. shape the longest' diameter of whichl s'greaterthan' the diameterof said crystallizerandthe shortest diameter of which is the same aszthe diameter of saidl crystallizer, hydrau-A licallyx operated. reciprocating pistons eachl of which comprises.; a. cylinder vone end of.- whichi is pivota'lly' secured'to said axial, support, .af piston within said.. cylinder, a;rod attached to said piston extending throughv one -end of said cylinder and pivotally attached to one of saidvanes, hydraulic iiuidlinlets at' each end of said: cylinder, means fori' carrying;` hydraulic' iluid for' said 'piston through .said axial reciprocatingsupport. exible tubes:attachedvtol saldi fluid carryingv means and to saidhydraulie fluid inlets in'said cylinder, and means fortransmittingforce with said: hydraulic fluid'to'sai'd pistons and tosaid vanes .at the'start otltsaidLintake and pumpstrokes` thereby providingi impetus for closing. and. opening of said vanes. 8:. A Vfractional crystallizer according to'claim Ilwherein. said' means for. moving 4solid Y granulaimaterial, throughY said. crystallzer` comprises' a reciprocating. hollow support extending; axially through: saidY crystallizer, a. plurality' of 'foldable perforatezconveyor;flights disposed at 'spaced intervals along'Y saidi'supporty and. secured thereto, saldofoldable conveyor .flights being -adapted to closezon; the. intake :stroke and open` on'l the. pump strokefto saidl support. said flights comprisng.a pair. ofvanes which when laid. flat take an ellipselikeeshape the longest diameter of which is Vgreatenftlian: the diameter of; said crystallizen an'd the 8 shortest-` diameter vof which isfthe samefa'sthe diameter-of said 'crystallizem hydraulically operiated .ireciprocating pistonsi each of 'which -com'- prisefiafcylinder 'one end of 'which' is pivotally securedrto saidr 'axial supportg'a'piston within said cylinder, an rod attached to said piston extending through. one lend-10i said cylinder and `pivotally attached. to one of said vanes, an hydraulic uid inlet'at each' end of said cylinder, means-forearrying hydraulic fluid for' said piston through. said axial.reciprocating` support,A means attached'to said'iluidcarryingl means and. extending-'through said axialsupport for fcarrying'saiduidgeidble tubes. attached theretoy to said hydraulic uid inletsl in` said cylinder,l a diverting mechanism for direeting'the-force' of saidl hydraulic fluidth-rough saidzinletleading to each side of said piston' comprising a .diverter valve, aI uid inlet-'tosaid valve for." uid under f pressurepoutlets from'` said lvalve for passing fluidf therefroml to each' offthef inlets to. said-'cylinders ai diverter within'fsaid valve which uponv movement deiieots tlie'incominp;y uld to "one-or thel other fof-said fluid outlets," means forl actuating .said- .diverter comprising. ',lugsf at tacl'ied` toy said axial support, so positioned thereon that the directioniof flow through said'valve isfchanged at the start' oflsaid intake stroke and saidpump` stroke; and outlet means Ifrom' said valveffor releasing .theforoe on the outlet oppositef'that throughwhich .force is instantly-being applied;` Y

DWIGHT L'.MoKMZQ No referenoes-citedl 

1. A FRACTIONAL CRYSTALLIZATION APPARATUS WHICH COMPRISES, IN COMBINATION, AN ELONGATED ENCLOSED CONTAINER, A PRODUCT OUTLET ADJACENT EACH END OF SAID CONTAINER AND A FEED INLET INTERMEDIATE SAID ENDS, MEAN FOR ADDING HEAT TO SAID CONTAINER ADJACENT ONE END THEREOF, MEANS FOR ABSTRACTING HEAT FROM SAID CONTAINER ALONG A PORTION THEREOF BETWEEN SAID FEED INLET AND THE UNHEATED END, AND MEANS FOR MOVING SOLID GRANULAR MATERIAL THROUGH SAID CONTAINER FROM THE COOLED TO THE HEATED END WHICH COMPRISES A RECIPROCATING SUPPORT EXTENDING AXIALLY THROUGH SAID CONTAINER, A PLURALITY OF FOLDABLE PERFORATE CONVEYOR FLIGHTS HINGED AT SPACED INTERVALS TO SAID ADAPTED TO CLOSE FOLDABLE CONVEYOR FLIGHTS BEING ADAPTED TO CLOSE ON THE INTAKE STROKE AND OPEN ON THE PUMP STROKE OF SAID FLIGHTS, AND A MOTOR PIVOTALLY ATTACHED TO SAID SUPPORTED AND SAID CONVEYOR FLIGHTS FOR APPLYING INPETUS TO THE CLOSING AND OPENING OF SAID CONVEYOR FLIGHTS. 